Field
Embodiments of the present invention relate to a semiconductor element drive device which drives a plurality of semiconductor elements configuring a power conversion device and which includes the function of notifying information necessary for protecting the semiconductor elements.
Discussion of the Background
Recently, an intelligent power module (IPM) has attracted attention. The intelligent power module is such that protection circuits for protection against anomalies, such as an overcurrent of the semiconductor element, a drop in the voltage of control power, and overheating, together with a semiconductor element formed of a power transistor, such as an IGBT, and its drive circuit, are modularized into one electronic component. Also, it is proposed in, for example, Japanese Publication No. JP-A-8-70580 that in addition to the plurality of protection circuits which detect the heretofore described respective anomalies, a notification circuit (an output circuit) which externally outputs an alarm signal with a preset pulse width in accordance with the type of the anomaly detected by each protection circuit is mounted on the intelligent power module. By including this kind of alarm signal notification circuit, a controller side which controls the drive device, for example, an inverter controller, by detecting the pulse width of the alarm signal, can distinguish the type of an anomaly occurring in a semiconductor element.
However, when a plurality of alarm signals with different pulse widths are output from the notification circuit at the same time, there is included the problem of it being difficult to distinguish between the alarm signals. Therefore, a semiconductor element drive device which avoids the heretofore described problem is disclosed in Japanese Publication JP-A-2012-143125, which, in general, makes it easy to distinguish between the alarm signals output as pulse signal trains. The semiconductor element drive device outputs one pulse's worth of alarm signal with a pulse width preset for each anomaly type, or outputs one pulse's worth of alarm signal after every present time interval, in accordance with a protection signal output from a protection circuit which has first detected an anomaly.
According to the semiconductor element drive device proposed in Japanese Publication JP-A-2012-143125, it does not happen that a plurality of types of alarm signals with different pulse widths are output at the same time. Consequently, it is easy to detect the pulse width of a notified alarm signal, and it is possible to accurately distinguish the type of an anomaly based on the pulse width of the detected alarm signal. However, when an anomaly of a semiconductor element is detected, it is only that one pulse's worth of alarm signal with a pulse width corresponding to the type of the anomaly is output, or that one pulse's worth of alarm signal is output after every preset time interval, meaning that there is the problem that even when the anomaly of the semiconductor element is cancelled, it is not possible to detect the cancellation.
In order to solve this kind of problem, for example, it is also conceivable to output an anomaly cancellation signal with a pulse width differing from that of the alarm signal by utilizing the fact that the outputs of the protection signals from the plurality of protection circuits stop when the anomaly of the semiconductor element is cancelled. However, in order that it is possible to clearly distinguish the anomaly cancellation signal, for example, when the pulse width of the anomaly cancellation signal is increased compared with that of the alarm signal, there arises the new problem that it takes a long time until the anomaly cancellation is detected.